thats the oneThat was me. Turnigy 9xr tray from HobbyKing. Fits Solo transmitter perfect, no screws required, just slides in very snug. Don't use the included rods though for the strap, they're flimsy and will break. Attach the balance strap to the rear metal stand off poles that separate the tray plates. Been using mine for months now, works excellent. Shame more people don't know about it.
9XR Radio Tray With Balance Strap (polycarbonate)